Many imaging devices are known for producing medical images of body lumens, such as the gastrointestinal (GI) tract. For example, endoscopy is widely used for observing, photographing tissue, and taking specimens from lesions and the like.
Tubular organs in the body may have a convoluted cavity configuration. The gastrointestinal tract, for example, starts from the oral cavity and proceeds through the esophagus, stomach, duodenum and small intestine, which is a long tube that folds many times to fit inside the abdomen. The small intestine is connected to the large intestine, which begins with the cecum, a small saclike evagination, then continues with the ascending colon, transverse colon, descending colon and the sigmoid (S-shaped) colon to the rectum. These body lumens may suffer from pathologies, which can affect the anatomy or configuration of the lumen. For example, strictures, narrowing or closure of a normally configured lumen can be caused by calcification or by the presence of scar tissue or a tumor.
Traditional colonoscopic examination utilizes a thin, tubular fiber optic probe inserted into the large intestine (colon) via the rectum. A conventional imaging endoscope used for such procedures comprises a flexible tube with a fiber optic light guide that directs illuminating light from an external light source to the distal tip of the endoscope where it illuminates the region (i.e., tissue, occlusive objects) to be examined.
Even the most penetrating colonoscopic inspections are limited to the colon and the terminal portion of the small intestine (ileum), due primarily to the tortuosity and fragility of the large intestine and ileum. Both endoscopic and colonoscopic inspections run a small but significant risk of physical damage to the patient, such as perforation of the duodenum or ileum, especially where disease has progressed to an advanced stage and the surrounding tissue has weakened or degenerated.
PCT Publication WO 05/065044 to Cabiri et al., which is incorporated herein by reference, describes apparatus for use with a biologically-compatible-fluid pressure source, the apparatus including an elongate carrier, adapted to be inserted through a proximal opening of a body lumen, and a piston head coupled to a distal portion of the carrier. The piston head is adapted to form a pressure seal with a wall of the lumen after the carrier has been inserted into the lumen, and to be advanced distally through the body lumen in response to pressure from the fluid pressure source. The apparatus is configured to facilitate distal advancement of the piston head by facilitating passage of fluid out of the lumen from a site within the lumen distal to the piston head. The apparatus additionally includes an optical system, coupled to the carrier in a vicinity of the distal portion, the optical system having distal and proximal ends.
In some embodiments of the PCT application, the apparatus is described as including an auxiliary piston head, coupled to the carrier at a position proximal to the distal piston head. The auxiliary piston head is described as being adapted to be inflated so as to attain and maintain direct contact with the wall of the colon. At least one time while the carrier is within the body lumen, the distal piston head is described as being adapted to be in a state of being already deflated at least in part simultaneously with the auxiliary piston head being already inflated and being advanced distally through the colon in response to pressure from the fluid pressure source. At least one other time while the carrier is within the body lumen, the auxiliary piston head is described as being adapted to be in a state of being already deflated at least in part simultaneously with the distal piston head being already inflated and being advanced distally through the colon in response to pressure from the fluid pressure source.
For example, the PCT application describes that the system may eventually reach an obstacle or tight turn. In such a case, the proximal piston head is described as being inflated and the distal piston head as being deflated. In this configuration, the pressurized fluid is described as creating greater fluid pressure acting on the proximal side of the proximal piston head than on the distal side of the proximal piston head. This pressure difference is described as propelling the proximal piston head together with the carrier distally. This distal movement brings the distal deflated piston head past the obstacle.
The system is described as continuing its distal movement in the body lumen until the proximal piston head reaches the obstacle. At this point, the distal piston head is described as being inflated and the proximal piston head as being deflated. The pressurized fluid is described as creating greater fluid pressure acting on the proximal side of the distal piston head than on the distal side of the distal piston head. The pressure difference is described as propelling the system distally in the body lumen, bringing the proximal deflated piston head past the obstacle. The cycle is described as being repeated as often as necessary.